A free email agroforestry journal for practitioners, extension agents, researchers, professionals, students, and enthusiasts. One edition is sent each month focusing on a concept related to designing, developing, and learning more about trees and agroforestry systems. Focuses on trees and their roles in agriculture, natural ecosystems, human culture and economy.

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Overstory #81 - The Soil Foodweb: It's Role in Ecosystem Health

The Soil Foodweb

What is the soil foodweb? It's the set of organisms that perform the functions that allow plants to grow normally, without the need for toxic chemical inputs. A set of healthy organisms, a healthy soil foodweb if you will, gives plants the following necessary functions:

Disease suppression.

A healthy foodweb includes thousands of species of bacteria and fungi, protozoa and nematodes all of whom combat diseases causing organisms. Unfortunately, they are among the first to be killed when using pesticides and high levels of inorganic fertilizers.

Nutrient retention.

Ever wonder why fertilizers have to be added every year in chemically intensive systems? Because it is the organisms in the healthy foodweb that retain those nutrients, and once those organisms are killed, soil cannot hold on to those nutrients. N, P, S, and calcium, as examples, will leach from the soil without the nutrient-retention abilities of the millions if not billions or more living bacteria and fungi that should be present in your soil.

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Overstory #80 - Forests and Water

Forests and Water

For eons, forests have been slowing water movement and thus precipitating sediments, capturing nutrients, and building the soil. The presence or absence of forest cover may decide the ultimate fate of human society.

Forests have an intimate relationship to water supplies. The delayed release of rainwater from forested soils of the uplands are vital to lowland water supplies. Litter that accumulates on the forest floor absorbs the physical impact of torrential downpours and releases the water gently to the mineral soil beneath. This cushioning action largely prevents the water from suspending large quantities of surface soil particles and thus clogging soil pores beneath. In addition, the decaying litter enriches the water entering the soil and supports organisms that produce porous upper soil layers. These processes are the most obvious ways forests enhance water supplies. The draft on soil water is greatest under forests with their deep-rooted trees and high rates of transpiration. Between storms porous soils again become highly receptive to new water.

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Overstory #79 - Creating an Internship

In this edition of The Overstory, we share our recommendations about ways to create a valuable internship experience. The authors have been both interns and mentors in sustainable agriculture. These tips for prospective interns may also be useful for those who would like to become a mentor or improve their internship process.


Practical, hands-on experience is a key part of learning to work with trees and forests. Many people of all ages and career paths are seeking ways to increase their practical skills through internships. Internships are short- or long-term practical experiences (usually between 1 - 12 months) supervised by a mentor. Frequently the mentor is not a school or university professor, but instead a farmer, agroforester, traditional plant gatherer, or other practitioner.

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Overstory #78 - Reforestation of Degraded Lands

This edition of The Overstory joins combines topics in preparation, species selection, planting materials, and tree maintenance towards reforesting degraded lands.


Degradation of tropical land is a physical, chemical, and biological process set in motion by activities that reduce the land's inherent productivity. This process includes accelerated erosion, leaching, soil compaction, decreased soil fertility, diminished natural plant regeneration, disrupted hydrological cycle, and possible salinization, waterlogging, flooding, or increased drought risk, as well as the establishment of undesirable weedy plants. There is a strong relationship between inappropriate land-use practices and land degradation. In some places, degradation is manifest (e.g., desertification), where in others it is inferred (e.g., declining crop yields).

Deforestation in mountainous regions is one of the most acute and serious ecological problems today. Disturbance of vegetative cover on montane areas with thin soil and steep slopes results in land instability (e.g., landslides) and soil erosion. Excessive erosion not only impairs site productivity but may also adversely affect other sites or water bodies farther down the watershed.

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Overstory #77 - Tropical Forest Conservation

Types of Tropical Forests

About half of all the world's forests are in the Tropics, the area between the Tropic of Cancer and the Tropic of Capricorn. In addition to rain forests, there are mangroves, moist forests, dry forests, and savannas. Such classifications, however, give only a slight indication of the diversity of tropical forests. One study by the Food and Agriculture Organization (FAO) of the United Nations, which considered 23 countries in tropical America, 37 in tropical Africa, and 16 in tropical Asia, identified dozens of types of tropical forests: open and closed canopy forests, broad leaved trees and conifer forests, closed forests and mixed forest grasslands, and forests where agriculture has made inroads.

Value of Tropical Forests

All forests have both economic and ecological value, but tropical forests are especially important in global economy. These forests cover less than 6 percent of the Earth's land area, but they contain the vast majority of the world's plant and animal genetic resources.

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Overstory #76 - Ethnoforestry

Introduction to Ethnoforestry

The effectiveness of traditional forest management practices has often been overlooked by the scientific community. This edition of The Overstory by special guest author Deep Narayan Pandey of the Indian Institute of Forest Management, Bhopal, India introduces the importance and application of ethnoforestry.

Towards the Equity of Knowledge

People throughout the world have effective traditional resource management systems including protection, production and conservation practices which they have validated over time. Many of these traditions have been incorporated into modern practices of scientific forestry by innovative foresters. We can define ethnoforestry as the creation, conservation, management and use of forest resources, through continued practice of customary ways by local communities. Thus, it is specific and appropriate to each community and environment.

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